We made the trip this year. So much to see and do.
After Banff you should head towards Lake Louise, The Ice Fields, Jasper, Revelstoke, Kamloops, Fairmont Hot Springs, Kelowna, Osoyoos (One of our favorite places - a good place to stay is Nk'Mip Campground), The Sea to Sky Highway from Vancouver to Whistler is a great drive (Whistler RV Park - great views, but steep hill to climb at the entrance).
British Columbia does a good job with their "Circle Tours", lots of info and recommendations. We just spent two months in the Victoria area.
If at all possible, stay at the West Bay Marina and RV Village, A great place to stay and explore Victoria (Book months in advance). Watch the Ferries come and go, the seaplanes take off and land. Take the water taxi to Fisherman's Wharf for fish and chips. Walk to downtown from the RV Park.
The other place we stayed was Oceanside RV Park close to Sidney which is about 20 minutes from Victoria. Take a side trip for a couple of days and go to Tofino if at all possible (Drive the toad).
We left Toronto August 1st on our Maiden Voyage in our Newmar Mountain Aire towing an F150 pick up truck. Lots of mountain driving with great views. After a while though, you'll be glad to see a flat straight level road, but the drive is more than worth it.
It may be worth it for you to buy the Parks Canada Discovery Pass, which gives you entrance into all the Parks.
Chuck and Jacquie